We're fans of the new breed of aftermarket GPS systems, with their instant setup and nifty features, but controlling them is still an issue. Touchscreens help, but we prefer Harman/Kai don's Guide + Play GPS 810 ($600, guideandplay.com), which has a wireless control knob you stick within reach of the driver. It offers the feel of a factory-inslalled GPS, but you can connect it yourself in less than five minutes.

We're fans of the new breed of aftermarket GPS systems, with their instant setup and nifty features, but controlling them is still an issue. Touchscreens help, but we prefer Harman/Kai don's Guide + Play GPS 810 ($600, guideandplay.com), which has a wireless control knob you stick within reach of the driver. It offers the feel of a factory-inslalled GPS, but you can connect it yourself in less than five minutes.